We all like hot water. It's not
essential, but it makes cleaning clothes and dishes much easier and
bathing our bodies more comfortable. Hygiene is important in
everyday life, and it becomes more important if TSHTF and medical
facilities are scarce or overloaded. Cold showers suck, and back when
I had to shave every day having hot water meant I could do so without
bleeding all over the place. Think about it: what's the first thing
you want to do after coming home from a camping trip or a long day of
hard work? A hot shower will be on the top of the list for most
people.
Type of Hot Water Heaters
Most homes and apartment
buildings will have a water heater hidden somewhere in a utility
closet or corner of the basement. Water heaters are a common
household appliance, but they have the potential to become bombs if
not maintained. I won't link to them, but there are plenty of videos
on the Internet of the devastation caused by exploding water heaters.
One of the insurance companies runs an ad on TV that mentions
covering damage from a water heater that landed on a neighbor's car.
Mythbusters covered them pretty well; the one video I saw had a 50
gallon tank launch itself 500 feet into the air. That's enough force
to send a hundred pounds of tank through several floors and walls.
Electricity, liquid propane (LP), or natural gas (NG) are the main
power sources for heating water, although I have seen wood-fired
water heaters and add-on heat exchangers for wood stoves. Remote or
limited-use facilities may have a tiny point-of-use heater tucked
under the sink to provide hot water for personal hygiene. There are
“tankless” water heaters available, but they're expensive and
require more maintenance. There are also municipal hot water systems in large cities that provide very hot water or steam to buildings near a generating plant (sometimes as a byproduct of generating electricity), but that's beyond our control, so the maintenance for it is outside the scope of prepping. The same goes for living in an apartment building, since the owner has control over the central utilities. Let's stick to the common tank style water
heaters that you'll find in home improvement stores for today.
Tank-style water heaters come in a
variety of sizes and use the three heat sources I mentioned
(electric, LP, or NG) depending on what's available. A lot of new
houses are “all-electric”, while rural areas lack the NG pipelines
found in town and have to rely on LP stored on-site. Electric units
don't need to be vented (no combustion, no exhaust) while the gas
units are more efficient and “recover” faster in my experience.
They all have the same basic design: a vertical tank with cold water
inlet and hot water outlet on the top, anode rod inserted through the
top, heat source at or near the bottom, drain valve on the bottom,
and a relief valve (T&P valve) on the side or top. They also all
share a few ways to ruin your day.
Temperature & Pressure
The T&P valve is a safety device
that will open and vent the tank if the temperature (T) or pressure
(P) gets too high. Water expands when heated, and some expansion is
expected and the tanks are engineered for it. Since water heaters are
a closed system except for when the water is in use, this expansion
leads to an increase in pressure. If the pressure gets above 150 psi,
the T&P valve should open and relieve the pressure by venting
water to a drain. The valve will also open if the temperature gets
to about 210°F, which is just short of boiling. Boiling water
produces steam, which takes up 1700 time as much space as liquid
water (at standard pressure). Water heater tanks are not designed as
boilers and will explode if the water inside starts to boil.
By most
building codes, the T&P valve has to be piped to a drain with an
air gap between the end of the pipe and the drain, so that you can
see water flowing if the valve opens or is leaking. Testing the T&P
valve a couple of times a year will let you know that it isn't
leaking, stuck, or plugged. Having a stuck or plugged relief valve is
the same as not having a relief valve, so read the instructions on
the tag or look up how to test your particular valve.
Hard Water and Sediment
If you have hard water or a lot of
sediment in your water, sand and scale will settle out on the bottom
of the tank. This layer of sediment will act as an insulator, causing
the heat source to run longer to heat up the water and potentially
overheat the water. A water heater that has a lot of sediment will
start to take longer to recover after use, so watch for longer
intervals between having hot water. If the thermostat sensor that
controls the heating element or burner gets covered, you can have a
runaway heater that will stay on until something pops.
The drain
valve on the bottom of the tank is there so you can shut the heater
down once a year and drain the sediment out. Most drain valves are
threaded for garden hose fittings, which makes it easy to connect to, but you don't want to run hot water through a garden hose because they'll melt. Instead, turn off the heat and either let the heater cool down or open a
faucet to let cold water in to cool it.
Popping
If you ever hear a “popping” noise
coming from your water heater while it's in operation, that's a sign
that you have scale building up. Water trapped between layers of
scale will boil and “pop” as the steam escapes into the water.
Old, limed-up teapots make the same noise and will often bounce or
move on the stove when they do. This is from the energy released by
the steam as it hits the water around it; now imagine your 40-50
gallon water heater “dancing” in the basement rather than a
half-gallon teapot on the stove.
Any movement of an appliance
attached to gas lines needs to be accounted for, so make sure your
gas line have a flexible section where it connects to the heater.
They're usually yellow in color to designate that they carry a
flammable gas. Gas leaks in a basement are a good way to destroy a
house! I've seen it happen a few times; one was fairly minor and it blew
out every window and lifted the house off of the foundation. A few
others I've driven by looked like a tornado had hit the house, with nothing but a hole in the ground surrounded by debris.
Rusting
Most tanks are made of steel and will
rust on the inside. This is minimized by the use of a sacrificial
anode rod of zinc or some other metal that is more reactive than
iron. The sacrificial rod will slowly erode over a few years and
should be replaced when it is almost gone. The rod is usually
threaded into the top of the tank and replacements can be found in
home improvement stores. If your hot water starts to look reddish or
develops a sulfur smell, it's time to replace the sacrificial rod; not replacing it means allowing the tank walls to get thinner as they
rust away, which reduces the pressure that it can withstand. That
rust will also add to the sediment building up on the bottom of the
tank that I mentioned above.
Avoiding trouble is one of the tenets
of prepping, so do your maintenance. If you have any doubts about your ability to work on anything, call a professional or get the training. Plumbers and electricians are expensive, but not as expensive as a house fire or cleaning up after burst pipes.
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